CN117470091A - A large-aperture interference phase shift measurement device based on Wollaston prism - Google Patents

Abstract

The invention discloses a large-caliber interference phase shift measuring device based on a Wollaston prism, which aims to solve the problem that the prior art is difficult to measure the global characteristic of a large-caliber measuring surface, so that accurate interference phase shift information feedback and fine global resolution capability cannot be obtained. The device specifically comprises a laser, a beam splitting prism and the like; the laser emits incident laser light; the beam splitting prism splits the incident laser beam into first reflected light and first transmitted light; the first transmission light is reflected by the mirror to be measured and the beam splitting prism in sequence to form measuring light; the first large-aperture reflector is arranged on the light path where the first reflected light is located to form reference light; the Wollaston prism is arranged on the light path where the measuring light and the reference light are located; the one-dimensional transmission grating is arranged on the light path where the o light and the e light are located; the first CCD camera, the second CCD camera, the third CCD camera and the fourth CCD camera are respectively arranged on the light path of one side of the one-dimensional transmission grating far away from the Wollaston prism so as to acquire interference information.

Description

A large-aperture interference phase shift measurement device based on Wollaston prism

Technical field

The invention relates to a large-aperture measurement device, and in particular to a large-aperture interference phase shift measurement device based on a Wollaston prism.

Background technique

Large-diameter measuring mirrors play an important role in high-end immersion lithography machines, large astronomical telescopes and other fields. Among them, the surface roughness, surface shape information, film thickness information, edge profile information and other parameters of large-diameter measuring mirrors are very important for high-end manufacturing. It is particularly important in the industrial field and the field of high-precision products, such as: large-diameter laser interferometer, optical surface profiler, laser scanner, etc. In order to achieve more accurate surface shape information parameter measurement, the current mainstream measurement methods are usually used, including interference surface shape measurement and non-interference surface shape measurement. Among them, the interference surface shape measurement method uses the coherence between beams to propagate during the beam propagation. During the process, the interference information of the beam superposition is formed to obtain the phase difference value change. The non-interference surface measurement method is to use the shadow fringes formed by laser projection images or grating projection images to resolve the fringe information, or use a contact method to obtain The height information of the surface at each place is used to splice the surface measurement information; compared with non-interference surface measurement, using the interferometric method for surface measurement can not only obtain a larger measurement range and measurement resolution, but also improve the measurement area. The fineness of the shape allows for more accurate surface shape measurement information. Therefore, in order to obtain high-precision height information of the global internal surface shape information, the dual beam expansion method and the double-layer spectroscopic method are combined to solve key technical problems such as insufficient surface shape measurement accuracy and incomplete surface shape measurement information, and meet the needs of large-diameter measuring mirrors. Large-aperture global measurement, ultra-precise surface measurement and phase feedback identification surface measurement requirements for accurately transmitting wavefront signals.

In order to achieve the purpose of large-aperture global measurement and high-precision measurement, the interference surface shape measurement method with laser wavelength as the benchmark is often used. The laser wavefront during the propagation process of the laser is used as the measurement benchmark. By solving the spatial superposition of the laser beam, Interference fringe signals are used to obtain the phase shift information carried, and the contrast changes are analyzed based on the energy change characteristics under different phase shift information to construct large-aperture measurement mirror surface shape information. For example: optical surface profilometer, which determines the accuracy of interference measurement by changing the moving optical path difference of interference fringes, can achieve mm-level measurement range and seamless big data splicing technology; there is also a precision scanning surface based on white light interference technology The profiler uses precision grating displacement sensors to collect data, fit and evaluate surface parameters, and uses various precision mechanical parts to measure point, angle, circle and other shape parameters and cross-sectional profile shape parameters. However, all of the above have not yet formed a complete high-precision surface shape measurement product that uses multi-disciplinary technology and multi-mode optical measurement technology for large-diameter global measurement. It is still necessary to focus on the basic principles and core technology levels to comprehensively measure large-diameter measuring mirrors. Accurate measurement levels within the situation to achieve the manufacturing of high-end non-contact interference large-diameter measuring instruments.

Contents of the invention

The purpose of the present invention is to provide a large-aperture interference phase shift measurement device based on a Wollaston prism to solve the problem that the existing technology is difficult to measure the global characteristics of a large-aperture measurement surface, resulting in the inability to obtain accurate interference phase shift information feedback and fine global resolution. Technical issues of capability.

In order to achieve the above purpose, the present invention provides a large-aperture interference phase shift measurement device based on a Wollaston prism, which is special in that it includes: a laser, a beam splitting prism, a first large-aperture reflector, a Wollaston prism, a one-dimensional transmission grating, The first CCD camera, the second CCD camera, the third CCD camera and the fourth CCD camera;

The laser emits incident laser light;

The dichroic prism is arranged on the optical path where the incident laser is located, and the incident laser is evenly split with energy to form the first reflected light and the first transmitted light; the mirror to be measured is arranged on the optical path where the first transmitted light is located, and the first transmitted light It is sequentially reflected by the mirror to be measured and the dichroic prism to form the measurement light;

The first large-diameter reflector is arranged on the optical path where the first reflected light is located, reflects the first reflected light and then enters the dichroic prism again, and is transmitted by the dichroic prism to form the reference light;

The Wollaston prism is arranged on the optical path of the measurement light and the reference light, and is used to separate the two into o-light and e-light respectively;

The one-dimensional transmission grating is arranged on the optical path where the o-light and the e-light are located, and is used to split the o-light and the e-light again to form the -1-order diffracted light and the 0-order diffracted light of the o-light and the 0-order diffracted light of the e-light. +1st order diffracted light;

The first CCD camera is arranged on the optical path where the -1 order diffracted light of the o-light of the measurement light and the reference light is located, and is used to feed back 0° phase shift interference information;

The second CCD camera is arranged on the optical path where the 0th order diffracted light of the o-light of the measurement light and the reference light is located, and is used to feed back 45° phase shift interference information;

The third CCD camera is arranged on the optical path where the +1 order diffracted light of the e-light of the measurement light and the reference light is located, and is used to feed back 90° phase shift interference information;

The fourth CCD camera is arranged on the optical path where the 0th order diffracted light of the e-light of the measurement light and the reference light is located, and is used to feed back 135° phase shift interference information.

Further, it also includes a first beam expander, a second beam expander and a third beam expander;

The first beam expander is arranged on the optical path between the laser and the dichroic prism, and its large end is opposite to the dichroic prism;

The second beam expander is arranged on the optical path between the dichroic prism and the first large-aperture reflector, and its large end is opposite to the first large-aperture reflector;

The third beam expander is arranged on the optical path between the dichroic prism and the mirror to be measured, and its big end is opposite to the mirror to be measured;

The beam expansion multiples of the second beam expander and the third beam expander remain consistent.

Further, it also includes a first converging lens, a second converging lens, a third converging lens and a fourth converging lens;

The first converging lens is disposed on the optical path between the one-dimensional transmission grating and the first CCD camera, and its converging end corresponds to the first CCD camera;

The second converging lens is disposed on the optical path between the one-dimensional transmission grating and the second CCD camera, and its converging end corresponds to the second CCD camera;

The third converging lens is disposed on the optical path between the one-dimensional transmission grating and the third CCD camera, and its converging end corresponds to the third CCD camera;

The fourth converging lens is disposed on the optical path between the one-dimensional transmission grating and the fourth CCD camera, and its converging end corresponds to the fourth CCD camera.

Further, it also includes a first polarizing plate, a second polarizing plate, a third polarizing plate, a fourth polarizing plate and a fifth polarizing plate;

The first polarizing plate is disposed on the optical path between the laser and the first beam expander;

The second polarizer is disposed on the optical path between the one-dimensional transmission grating and the first converging lens;

The third polarizing plate is disposed on the optical path between the one-dimensional transmission grating and the second condensing lens;

The fourth polarizing plate is disposed on the optical path between the one-dimensional transmission grating and the third converging lens;

The fifth polarizing plate is disposed on the optical path between the one-dimensional transmission grating and the fourth condensing lens.

Further, the laser is a single-frequency laser.

Further, the mirror to be tested is a second large-diameter reflector.

Furthermore, it also includes a third largest-diameter reflector;

The mirror to be tested is a large-diameter transmission mirror;

The third large-diameter reflective mirror is arranged on the optical path of the side of the large-diameter transmission mirror away from the dichroic prism.

Furthermore, it also includes a standard first spherical mirror;

The mirror to be tested is a second spherical mirror;

The first spherical mirror is disposed on the optical path between the dichroic prism and the second spherical mirror, and the focal points of the first spherical mirror and the second spherical mirror coincide with each other.

Further, it also includes a sixth polarizing plate;

The laser is a dual-frequency laser;

The beam splitting prism is a polarizing beam splitting prism;

The sixth polarizer is disposed on the optical path between the polarizing beam splitter prism and the Wollaston prism.

Further, it also includes a first quarter-wave plate and a second quarter-wave plate;

The first quarter-wave plate is disposed on the optical path between the polarizing beam splitter prism and the second beam expander;

The second quarter-wave plate is disposed on the optical path between the polarizing beam splitter prism and the third beam expander.

Beneficial effects of the present invention:

1. The present invention uses a one-dimensional transmission grating and a Wollaston prism for double-layer spectroscopy to achieve accurate phase shift detection characteristics. At the same time, the Wollaston prism polarization characteristics and polarization spectroscopy interference characteristics are used to obtain highly accurate global interference fringe information, making the large-aperture The interferometric phase shift measurement device has the advantages of global large-aperture interferometry, ultra-precise interference phase shift information feedback and high-precision global resolution capabilities. It is the development of large-aperture surface shape detection and large-aperture profile measurement in the international market. This method is also an important demand for high-end manufacturing fields and high-precision industrial production fields.

2. The present invention is based on double beam expansion and Wollaston prism spectroscopy, and features a phase shift structure formed by a one-dimensional grating and a polarizer to achieve large-aperture interference phase shift measurement. Not only can it be used for multiple wavelengths to improve the global measurement resolution, but it can also simplify the cost of a large-aperture surface measurement device, obtain accurate phase measurement values from multiple different polarization characteristics, and also eliminate fuzzy phase measurement values due to periodic changes, so , The large-aperture interference phase shift measurement device based on Wollaston prism proposed by the present invention not only takes into account the large-aperture global situation measurement, but also satisfies the global accurate surface shape information feedback and phase shift information changes under different polarization characteristics. Obtain high-precision alignment measurement information to improve large-diameter surface shape measurement resolution.

Description of the drawings

Figure 1 is a schematic structural diagram of Embodiment 1 of a large-aperture interference phase shift measurement device based on Wollaston prisms of the present invention;

Figure 2 is a partial structural schematic diagram of Embodiment 2 of a large-aperture interference phase shift measurement device based on Wollaston prisms of the present invention;

Figure 3 is a partial structural schematic diagram of Embodiment 3 of a large-aperture interference phase shift measurement device based on Wollaston prisms of the present invention;

Figure 4 is a partial structural schematic diagram of Embodiment 4 of a large-aperture interference phase shift measurement device based on Wollaston prisms of the present invention.

Reference number:

1-laser, 201-first polarizer, 202-second polarizer, 203-third polarizer, 204-fourth polarizer, 205-fifth polarizer, 206-sixth polarizer, 301-first Beam expander, 302-the second beam expander, 303-the third beam expander, 4-beam splitting prism, 501-the first large-aperture reflector, 502-the second large-aperture reflector, 503-the third large-aperture reflection Mirror, 6-Wollaston prism, 7-one-dimensional transmission grating, 801-first converging lens, 802-second converging lens, 803-third converging lens, 804-fourth converging lens, 901-first CCD camera, 902 - The second CCD camera, 903 - The third CCD camera, 904 - The fourth CCD camera, 10 - Polarizing beam splitter prism, 1201 - The first spherical mirror, 1202 - The second spherical mirror, 13 - Large aperture transmission mirror.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

Example 1:

As shown in Figure 1, a large-aperture interference phase shift measurement device based on a Wollaston prism, a large-aperture interference phase shift measurement device based on a Wollaston prism, includes a laser 1, a dichroic prism 4, a first large-aperture mirror 501, Wollaston prism 6, one-dimensional transmission grating 7, first CCD camera 901, second CCD camera 902, third CCD camera 903, fourth CCD camera 904, first beam expander 301, second beam expander 302, third Beam expander 303, first condenser lens 801, second condenser lens 802, third condenser lens 803, fourth condenser lens 804, first polarizer 201, second polarizer 202, third polarizer 203, fourth polarizer plate 204 and the fifth polarizing plate 205.

Laser 1 emits 632.8nm incident laser with a certain polarization state, and is a single-frequency laser. The dichroic prism 4 is arranged on the optical path where the incident laser is located, and evenly splits the incident laser light with energy to form the first reflected light and the first transmitted light; the mirror to be measured is arranged on the optical path where the first transmitted light is located, and the first transmitted light is passed through in turn. The measurement mirror and the dichroic prism 4 reflect to form measurement light; the mirror to be measured is the second largest diameter reflector 502. The first beam expander 301 is disposed on the optical path between the laser 1 and the dichroic prism 4, and its large end is opposite to the dichroic prism 4 for the first beam expansion; the first polarizer 201 is disposed between the laser 1 and the first beam expander 301. The optical path between the beam expanders 301 is used to adjust the polarization state of the incident laser; the third beam expander 303 is arranged on the optical path between the dichroic prism 4 and the mirror to be measured, and its big end is opposite to the mirror to be measured. The second beam expansion is performed based on the first beam expansion. The first large-diameter reflector 501 is disposed on the optical path where the first reflected light is located. It reflects the first reflected light and then enters the dichroic prism 4 again, and is transmitted by the dichroic prism 4 to form the reference light. The first large-diameter reflector 501 serves as The standard plane of the entire large-aperture measuring device is used as a reference plane; the second beam expander 302 is arranged on the optical path between the beam splitter prism 4 and the first large-aperture reflector 501, and its big end is opposite to the first large-aperture reflector 501. , used to perform the second beam expansion based on the first beam expansion. The Wollaston prism 6 is set on the optical path of the measurement light and the reference light, and is used to separate the two into o-light and e-light according to different polarization characteristics. The o-light and e-light both contain two different polarization characteristics or two polarized light with the same polarization characteristics. The one-dimensional transmission grating 7 is arranged on the optical path where the o-light and the e-light are located, and is used to split the o-light and the e-light again according to the different grating lines of the one-dimensional transmission grating 7 to form -1-order diffraction light and 0-order diffraction light of the o-light. As well as the 0th order diffraction light and the +1th order diffraction light of e-light; o-light and e-light pass through the one-dimensional transmission grating 7, the polarization state of the linearly polarized light remains unchanged, and the polarization state of other polarized light changes at different angles, without The diffracted light will simultaneously carry different phase difference values of the one-dimensional transmission grating 7, which are +Δφ and -Δφ respectively. The first CCD camera 901 is arranged on the optical path where the -1 order diffracted light of the o light is located, and is used to receive the interference light signal of the -1 order diffracted light after the o light is diffracted; the first converging lens 801 is arranged on the one-dimensional transmission grating 7 and On the optical path between the first CCD camera 901, its convergence end corresponds to the first CCD camera 901, and is used to converge the interference light signal of the -1 order diffracted light after the o-light is diffracted; the second polarizer 202 is arranged in one-dimensional transmission The optical path between the grating 7 and the first condensing lens 801 is used to adjust the polarization state of the −1 order diffracted light after the o-light has been diffracted. The second CCD camera 902 is disposed on the optical path where the 0th-order diffracted light of the o-light is located, and is used to receive the interference light signal of the 0th-order diffracted light after diffraction of the o-light; the second converging lens 802 is disposed between the one-dimensional transmission grating 7 and the second On the optical path between the CCD cameras 902, its convergence end corresponds to the second CCD camera 902, and is used to converge the interference light signal of the 0th order diffracted light after the o-light is diffracted; the third polarizer 203 is disposed between the one-dimensional transmission grating 7 and The optical path between the second condensing lenses 802 is used to adjust the polarization state of the 0th order diffracted light after the split o-light is diffracted. The third CCD camera 903 is disposed on the optical path where the +1st-order diffracted light of the e-light is located, and is used to receive the interference light signal of the +1st-order diffracted light after the e-light is diffracted; the third converging lens 803 is disposed between the one-dimensional transmission grating 7 and On the optical path between the third CCD camera 903, its convergence end corresponds to the third CCD camera 903, and is used to converge the interference light signal of the +1 order diffracted light after the e-light is diffracted; the fourth polarizer 204 is arranged in one-dimensional transmission The optical path between the grating 7 and the third condensing lens 803 is used to adjust the polarization state of the +1st order diffracted light after the e-light has been diffracted. The fourth CCD camera 904 is disposed on the optical path where the 0th-order diffracted light of the e-light is located, and is used to receive the interference light signal of the 0th-order diffracted light after diffraction of the e-light. The fourth converging lens 804 is disposed on the optical path between the one-dimensional transmission grating 7 and the fourth CCD camera 904. Its converging end corresponds to the fourth CCD camera 904 and is used to converge the interference light of the 0th order diffracted light after the e-light is diffracted. Signal. The fifth polarizing plate 205 is disposed on the optical path between the one-dimensional transmission grating 7 and the fourth condensing lens 804, and is used to adjust the polarization state of the 0th order diffracted light after the split e-light is diffracted.

Specifically, the single-frequency laser 1 emits incident laser light that is transmitted through the first polarizer 201 to change the polarization state of the incident light, and is incident on the first beam expander 301 for the first beam expansion. The beam expansion is the incident light of the single-frequency laser 1 The laser beam is split according to the energy of the dichroic prism 4. The reflected light is incident on the second beam expander 302 as a reference signal for the second beam expansion, and is reflected by the first large-diameter reflector 501. Among them, the first large-diameter reflector 501 is the standard The reference mirror, according to the reversible characteristics of the optical path, returns the reflected light along its original path, and is transmitted again through the second beam expander 302 and the dichroic prism 4 to form the reference light; the light transmitted by the incident laser through the dichroic prism 4 is incident to the third expanded beam as a measurement signal. The second beam expander 303 performs the second beam expansion and is reflected by the second largest diameter mirror 502, where the second largest diameter mirror 502 is the mirror to be measured. According to the reversible characteristics of the optical path, the transmitted light returns to the original path and passes through the second beam expander 303. The measurement light is formed by transmission and reflection by the dichroic prism 4; the two beams of reference light and measurement light generated by the dichroic prism 4 interfere with the same optical path and are incident on the Wollaston prism 6 for the first splitting, which is divided into o light and e light, where o light and The e-light contains the vertically polarized light and horizontally polarized light of the measurement light and the vertically polarized light and the horizontally polarized light of the reference light respectively. The phase difference between the two is π/2. Then the o-light and the e-light are incident on the one-dimensional transmission at a certain angle. The grating 7 performs the second splitting, and the four diffracted lights formed are -1 order diffraction light and 0 order diffraction light of o light, 0 order diffraction light and +1 order diffraction light of e light, among which, after the second The polarizer 202 transmits and fine-tunes the polarization state of the -1 order diffracted light of the o-light, and converges it on the detection surface of the first CCD camera 901 through the first condensing lens 801, and feeds back the interference information on the control surface of the first CCD camera 901. The shift is changed into the phase superposition of the phase characteristics of the vertically polarized light and the negative phase shift characteristics of the grating; the 0th-order diffracted light of the o-light is transmitted through the third polarizer 203, and the polarization state of the 0th-order diffracted light of the o-light is finely adjusted. The converging lens 802 converges on the detection surface of the second CCD camera 902, and feeds back the interference information on the control surface of the second CCD camera 902, in which the phase shift is changed into a phase superposition of the phase characteristics of the vertically polarized light and the phase shift characteristics of the grating; The +1st order diffracted light is transmitted through the fourth polarizer 204, and the polarization state of the +1st order diffracted light of the e-light is fine-tuned, and is converged on the detection surface of the third CCD camera 903 through the third condensing lens 803. The control surface feeds back interference information, in which the phase shift is changed into a phase superposition of the phase characteristics of the horizontally polarized light and the forward phase shift characteristics of the grating; the 0th order diffraction light of the e-light is transmitted through the fifth polarizer 205 to fine-tune the 0th-order diffraction of the e-light. The polarization state of the light is converged on the detection surface of the fourth CCD camera 904 through the fourth converging lens 804, and the interference information is fed back to the control surface of the fourth CCD camera 904, where the phase shift is changed into the phase characteristics of the horizontally polarized light and the grating phase shift. Characteristic phase superposition; the -1 order diffraction light of the o light signal of the reference light transmitted through the one-dimensional transmission grating 7 interferes with the -1 order diffraction light of the o light signal of the measurement light transmitted through the one-dimensional transmission grating 7, forming a 0° phase shift signal; the o-light signal of the reference light interferes with the 0th-order diffracted light transmitted through the one-dimensional transmission grating 7 and the o-light signal of the measurement light passes through the one-dimensional transmission grating 7, forming a 45° phase-shifted signal; reference The e-light signal of the light interferes with the +1-order diffracted light transmitted through the one-dimensional transmission grating 7 and the +1-order diffracted light of the measurement light transmitted through the one-dimensional transmission grating 7 to form a 90° phase shift signal; the reference light The 0th order diffracted light of the e-light signal transmitted through the one-dimensional transmission grating 7 interferes with the 0th-order diffracted light of the measurement light e-light signal transmitted through the one-dimensional transmission grating 7 to form a 135° phase shift signal. Four beams of diffracted light form a four-step phase shift structure and are incident on the CCD camera respectively; the double beam expansion multiples of the reference light and the measurement light remain the same, the phase shift information carried by the two splits is different, and the phase shift states of different polarization changes are are different, and the surface shape information is solved according to the phase shift interference signal under different polarization characteristics; this structure can not only accurately improve the overall in-plane measurement resolution, but also obtain accurate phase measurement values under multiple different polarization characteristics, so as to Achieve clear and reliable large-diameter surface measurement purposes.

Example 2:

As shown in Figure 2, the structure of this embodiment is basically the same as that of Embodiment 1. The difference is that the mirror to be measured is a second spherical mirror 1202, and a first spherical mirror 1201 is provided between the second spherical mirror 1202 and the third beam expander 303. . The expanded beam formed after the second beam expansion is the reference beam and the measurement light. The reference light can not only use the high-precision large-diameter mirror 501 as the standard reference mirror for surface shape measurement, but also use the standard large-diameter spherical mirror as the The standard reference mirror is used for surface shape measurement, that is, the transmitted light is transmitted through the first spherical mirror 1201 and is incident on the second spherical mirror 1202. The first spherical mirror 1201 is a spherical mirror standard lens. It only needs to ensure that the focus coincides. According to the principle of reversible optical path, the transmitted light By returning to the original path and generating interference fringes with the reference beam, the surface quality of the second spherical mirror 1202 can be judged based on the shape of the interference fringes.

Embodiment three:

As shown in Figure 3, the structure of this embodiment is basically the same as that of Embodiment 1. The difference is that the mirror to be tested is a large-diameter transmission mirror 13; the large-diameter transmission mirror 13 also has an optical path on the side away from the third beam expander 303. The third large-diameter mirror 503 can be the same large-diameter mirror as the first large-diameter mirror 501 . The expanded beam formed after the second beam expansion is the reference light and the measurement light. The reference light surface can use the high-precision third largest diameter mirror 503 as the standard reference mirror for surface shape measurement. The transmitted light passes through the large diameter transmission mirror. 13 is transmitted, and is incident on the third largest diameter mirror 503. The third largest diameter mirror 503 is a standard plane mirror lens. It only needs to ensure that the measurement light passes through the large diameter transmission mirror 13 in the entire area. According to the principle of reversible optical path, the transmitted light It returns to the original path and is transmitted through the large-aperture transmission mirror 13 and the third beam expander 303, and generates interference fringes with the reference light. The surface shape of the large-aperture transmission mirror 13 is judged by the optical path change characteristics of the interference light path or the interference fringe change characteristics. quality.

Embodiment 4:

As shown in Figure 4, the structure of this embodiment is basically the same as that of Embodiment 1, except that the laser 1 is a dual-frequency laser. The running examples under different polarization characteristics are divided into two:

The first is that the original measurement optical path does not change. The dual-frequency laser 1 emits two orthogonal linearly polarized lights, which are split according to energy through the dichroic prism 4. Both the reference signal and the measurement signal include two polarization states that are perpendicular to each other. The beam of light is respectively the vertical polarized light of the measurement signal, the horizontal polarized light of the measurement signal, the vertical polarized light of the reference signal and the horizontal polarized light of the reference signal; after being split by Wollaston prism 6, it is the vertical polarized light of the measurement signal and the reference signal respectively. The o-light formed by the vertically polarized light, the e-light formed by the horizontally polarized light of the measurement signal and the horizontally polarized light of the reference signal are respectively incident on the one-dimensional transmission grating 7 to form four beams of diffracted light, respectively: - of the o-light The interference light formed by the 1st order diffracted light, the interference light formed by the 0th order diffracted light of o light, the interference light formed by the 0th order diffracted light of e light, the interference light formed by the +1st order diffracted light of e light; each beam interferes The light contains both the reference light with frequency f1 and the measurement light with frequency f2. While forming a comparison, it can achieve accurate surface shape measurement of the interference light signals under different polarization characteristics.

The second reason is that some optical components have changed in the original measurement light path. The dichroic prism 4 can be replaced by the polarizing dichroic prism 10. The expanded beam after the first expansion is polarized and split by the polarizing dichroic prism 10, and the vertically polarized light is incident on the reference light path. , is transmitted through the first quarter-wave plate 1101, undergoes a second beam expansion through the second beam expander 302, is vertically incident on the first large-aperture mirror 501 for reflection, returns to the original path, and passes through the second beam expander 302 transmission and the first quarter wave plate 1101, the vertically polarized light becomes horizontally polarized light, which is transmitted through the polarizing beam splitting prism 10 to form the reference light; the horizontally polarized light is transmitted through the polarizing beam splitting prism 10 and passes through the second quarter wave plate 1101. The first wave plate 1102 is transmitted, is incident on the third beam expander 303 for the second beam expansion, is vertically incident on the second large-aperture mirror 502 for reflection, returns along the original path, is transmitted through the third beam expander 303 and the second fourth beam is expanded. The half-wave plate 1102 transmits the horizontally polarized light into vertically polarized light and is reflected by the polarizing beam splitter prism 10 to form measurement light. The reference light and measurement light are transmitted through the sixth polarizer 206 to the Wollaston prism 6 and are split by the Wollaston prism 6 It is o light and e light, and contains both reference and measured vertical polarization information and reference and measured horizontal polarization information. It is transmitted and split through the one-dimensional transmission grating 7 to form four beams of diffracted light, which are -1 order diffracted light of o light. The 0th order diffracted light of o light, the +1st order diffracted light of e light, and the 0th order diffracted light of e light. Four beams of diffracted light change the polarization state through different polarizers to achieve a four-step phase shift structure, namely phase shift interference fringes of 0°, 45°, 90°, and 135°, thereby solving the phase shift within the same 2π period. Move the variable.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be covered by the protection scope of the present invention. . Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (10)

1. A large-caliber interference phase shift measuring device based on a Wollaston prism is characterized in that: the device comprises a laser (1), a beam splitting prism (4), a first large-aperture reflecting mirror (501), a Wollaston prism (6), a one-dimensional transmission grating (7), a first CCD camera (901), a second CCD camera (902), a third CCD camera (903) and a fourth CCD camera (904);

the laser (1) emits an incident laser light;

the beam splitting prism (4) is arranged on the light path of the incident laser, and uniformly splits the incident laser with energy to form first reflected light and first transmitted light; the first transmission light is reflected by the mirror to be measured and the beam splitting prism (4) in sequence to form measuring light;

the first large-aperture reflector (501) is arranged on an optical path where the first reflected light is located, reflects the first reflected light, then enters the beam splitting prism (4) again, and is transmitted by the beam splitting prism (4) to form reference light;

the Wollaston prism (6) is arranged on the light path where the measuring light and the reference light are located and is used for respectively splitting the measuring light and the reference light into o light and e light;

the one-dimensional transmission grating (7) is arranged on the light path where the o light and the e light are located and is used for splitting the o light and the e light again to form-1-order diffraction light and 0-order diffraction light of the o light and 0-order diffraction light and +1-order diffraction light of the e light;

the first CCD camera (901) is arranged on an optical path where o-light-1-level diffraction light of the measuring light and the reference light is located and is used for feeding back 0-degree phase shift interference information;

the second CCD camera (902) is arranged on an optical path where o-ray 0-order diffraction light of the measuring light and the reference light is located and is used for feeding back 45-degree phase shift interference information;

the third CCD camera (903) is arranged on an optical path where e light +1-order diffraction light of the measuring light and the reference light is located and is used for feeding back 90-degree phase shift interference information;

the fourth CCD camera (904) is arranged on an optical path where e-ray 0-order diffraction light of the measuring light and the reference light is located and is used for feeding back 135-degree phase shift interference information.

2. The Wollaston prism-based large-caliber interferometric phase shift measurement device of claim 1, wherein: the beam expander further comprises a first beam expander (301), a second beam expander (302) and a third beam expander (303);

the first beam expander (301) is arranged on a light path between the laser (1) and the beam splitting prism (4), and the large end of the first beam expander is opposite to the beam splitting prism (4);

the second beam expander (302) is arranged on the light path between the beam splitting prism (4) and the first large-aperture reflecting mirror (501), and the large end of the second beam expander is opposite to the first large-aperture reflecting mirror (501);

the third beam expander (303) is arranged on a light path between the beam splitting prism (4) and the mirror to be detected, and the large end of the third beam expander is opposite to the mirror to be detected;

the beam expansion multiples of the second beam expander (302) and the third beam expander (303) are kept consistent.

3. The Wollaston prism-based large-caliber interferometric phase shift measurement device of claim 2, wherein: further comprising a first converging lens (801), a second converging lens (802), a third converging lens (803) and a fourth converging lens (804);

the first converging lens (801) is arranged on a light path between the one-dimensional transmission grating (7) and the first CCD camera (901), and the converging end of the first converging lens corresponds to the first CCD camera (901);

the second converging lens (802) is arranged on an optical path between the one-dimensional transmission grating (7) and the second CCD camera (902), and the converging end of the second converging lens corresponds to the second CCD camera (902);

the third converging lens (803) is arranged on the light path between the one-dimensional transmission grating (7) and the third CCD camera (903), and the converging end of the third converging lens corresponds to the third CCD camera (903);

the fourth converging lens (804) is arranged on an optical path between the one-dimensional transmission grating (7) and the fourth CCD camera (904), and the converging end of the fourth converging lens corresponds to the fourth CCD camera (904).

4. A Wollaston prism-based large aperture interferometric phase shift measurement device in accordance with claim 3, wherein: further comprising a first polarizer (201), a second polarizer (202), a third polarizer (203), a fourth polarizer (204), and a fifth polarizer (205);

the first polaroid (201) is arranged on an optical path between the laser (1) and the first beam expander (301);

the second polaroid (202) is arranged on the light path between the one-dimensional transmission grating (7) and the first convergent lens (801);

the third polaroid (203) is arranged on the light path between the one-dimensional transmission grating (7) and the second converging lens (802);

the fourth polaroid (204) is arranged on the light path between the one-dimensional transmission grating (7) and the third converging lens (803);

the fifth polaroid (205) is arranged on the light path between the one-dimensional transmission grating (7) and the fourth convergent lens (804).

5. The Wollaston prism-based large caliber interferometric phase shift measuring device according to any one of claims 1-4, wherein: the laser (1) is a single-frequency laser.

6. The Wollaston prism-based large caliber interferometric phase shift measuring device of claim 5, wherein: the mirror to be measured is a second large-caliber reflecting mirror (502).

7. The Wollaston prism-based large caliber interferometric phase shift measuring device of claim 5, wherein: further comprising a third large aperture mirror (503);

the mirror to be detected is a large-caliber transmission mirror surface (13);

the third large-caliber reflecting mirror (503) is arranged on an optical path of the large-caliber transmission mirror surface (13) far away from one surface of the beam splitting prism (4).

8. The Wollaston prism-based large caliber interferometric phase shift measuring device of claim 5, wherein: also included is a standard first spherical mirror (1201);

the mirror to be detected is a second spherical mirror (1202);

the first spherical mirror (1201) is arranged on the optical path between the beam splitting prism (4) and the second spherical mirror (1202), and the focal points of the first spherical mirror (1201) and the second spherical mirror (1202) are overlapped.

9. The Wollaston prism-based large caliber interferometric phase shift measuring device according to any one of claims 1-4, wherein: further comprising a sixth polarizer (206);

the laser (1) is a dual-frequency laser;

the beam-splitting prism (4) is a polarization beam-splitting prism;

the sixth polarizer (206) is arranged on the light path between the polarization splitting prism and the Wollaston prism (6).

10. The Wollaston prism-based large aperture interferometric phase shift measurement device of claim 9, wherein: also included is a first quarter wave plate (1101) and a second quarter wave plate (1102);

the first quarter wave plate (1101) is arranged on an optical path between the polarization beam splitter prism and the second beam expander (302);

the second quarter wave plate (1102) is arranged on the optical path between the polarization splitting prism and the third beam expander (303).